Effects of Electron Beam Irradiation on the Physicochemical Properties of Quinoa and Starch Microstructure

Quinoa (Chenopodium quinoa Willd.) is treated with electron beam irradiation (EBI) at doses of 0, 1, 2, 4, and 8 kGy. The effects of EBI on physicochemical and structural properties are investigated. The mean size of quinoa granules and starch and the amylose content of quinoa increase as the irradiation dose increases. The storage and loss moduli of quinoa flour decline after irradiation. The swelling ability of quinoa flour does not significantly change within the irradiation dose between 0 and 4 kGy. The solubility of quinoa flour increases significantly when quinoa is irradiated at an irradiation dose of >4 kGy. Differential scanning calorimetry (DSC) results indicate that the changes in enthalpy significantly decrease after irradiation, whereas EBI does not significantly change other DSC parameters. All the viscosity parameters of quinoa flour in a Rapid Visco Analyzer significantly decline after EBI. X-ray diffraction reveals that the relative crystallinity of starch decreases after irradiation. Scanning electron microscopy shows that irradiation does not damage the microstructure of quinoa starch. The contents of slowly digestible and resistant starches of quinoa starch increase as the irradiation dose increases. Fourier transform infrared spectroscopy indicates that no new chemical groups in starch are formed.